Field of Invention
The present invention relates to a coating technique, and more particularly to a wet coating method.
Description of Related Art
As electronic devices are increasingly compact, volumes of various components of the electronic devices are greatly shrunk. In addition, due to popularization of portable electronic devices and availability of wearable electronic devices, surface coating apparatuses, which can provide coating treatments with high precision, are needed for satisfying developing requirements of the electronic devices.
However, flatness of films formed by using typical coating treatments for compact electronic components has not satisfied the requirements of the electronic devices, which continue to be scaled down. Specifically to optical films or transparent films, tolerant margin of error of these films is only of nanometer order. In addition, for a substrate with a lower fusion point or lower hardness, such as a plastic substrate, because the substrate cannot sustain high temperature, current film-coating techniques for compact electronic components can only use low temperature methods to treat a coating coated on a surface of the substrate for converting the property of the coating. Thus, choices of the coatings are limited and sometimes films with desirable functions cannot be successfully formed on the substrates.